Porcine neuropeptide Y (pNPY) is a 36 amino acid residue peptide that belongs to a unique family of peptides having a wide distribution throughtout the central and peripheral nervous systems. Receptors for NPY are found in the central nervous system and in the periphery. In the brain, NPY is a potent stimulator of food intake, stimulates leutinizing hormone, growth hormone and prolactin, and produces cardiovascular depression. NPY is also a potent peripheral vasoconstrictor and has been reported to cause transient myocardial ischaemia in patients with angina pectoris. Agents which are agonists of these receptors are expected to increase appetite, decrease sexual behavior, decrease thyroid stimulating hormone, prolactin, leutenizing hormone and therefore would be useful as contracptive agents, to diminish sex drive in sex offenders, and in the treatment of reproductive-system related disorders, such as precocious puberty, endometriosis, breast tumors, prostate tumors, and decrease growth hormone levels by stimulating release and to act as peripheral vasodilators and therefore act as hypotensive agents. The compounds of this invention could be used in the treatment of eating disorders such as anorexia nervosa.